Just got iPhoned & iClouded!

I have been using cell phones for over 17 years- have used several phones from the Bricky Motorolas to Nokias, RIMs and finally the iPhone and the iCloud recently.Have been with all the major carriers. All these years have kept the same number and just transfered the data every time there was a change...either to the device or to the carrier. No problem - until NOW! When I cracked the glass on the iPhone the Palo Alto Apple support team was kind enough to swap me with a replacement phone and transfered the data through iCloud! Took less than a few minutes. Didnt bother to check the details...as everything seemed so cool! Today I was searching for a couple of songs on my phone....couldn't find it!! Got a call from a friend whose number has been on my contact for all my cell phone experiences....but my iPhone didn't recognise it. Surprised I went through theContact list to see if I had accidentally swapped the first name and last name...no such luck. On closer scrutiny I find that my contact list disappeared from U through Z. How convenient? Losing my contacts and songs through the cloud.....I know I should have backed up....well I thought thats what ICloud was doing???? Growing pain or just need to get used to these king of glitches with a hyper groeth company??